Pine oil, which can be derived as an essential oil from Pinus sylvestris, or alternatively, produced synthetically by acid-catalyzed reactions of terpenic hydrocarbons, alcohols, or diols in an aqueous media, comprises a variety of components, including a variety of terpenic alcohols. Of these terpenic alcohols, terpineol, which is a mixture of several tertiary alcohol isomers, including α-terpineol, β-terpineol, γ-terpineol, and 4-terpineol, has a pleasant floral odor similar to lilac and is widely used in high quality grades in consumer products in the fragrance and flavor industry. Along with terpineol, which has a boiling point of approximately 219° C. at normal pressure, several secondary terpenic alcohols, including fenchol and borneol which have boiling points of approximately 201° C. and 213° C. at normal pressure, respectively, are present in untreated pine oil, as well as other constituents, including various other terpenic alcohols, terpenic carbonyl compounds, terpene hydrocarbons, water, and other impurities. Separating terpineol from these and other constituents, as well as other low boiling impurities in pine oil, can be done relatively effectively and efficiently by employing traditional separation techniques given the differences in boiling points and solubilities.
However, although terpineol can be readily separated from water and other low boiling constituents in pine oil, terpineol cannot be readily separated from the secondary alcohols in pine oil, particularly fenchol and borneol. This is due to all three components having relatively similar boiling points, which does not allow the components to be separated easily by traditional separation techniques, particularly through distillation. Specifically, separating terpineol from borneol is an especially difficult task, since borneol co-distills with terpineol. Therefore, in order to sufficiently separate borneol from terpineol, multiple distillations or multiple other physical separations are usually required, which are not only time consuming, but are also energy inefficient, expensive to perform, can create a large amount of waste, and can denature the original terpineol in the pine oil, thus reducing the overall terpineol yield. Additionally, in order to produce high grade quality terpineol for acceptance by the consumer products industry, the terpineol has to satisfy strict requirements for purity, which is usually approximately 99% pure, as well as match industry odor standards. Accordingly, even relatively small amounts of impurities, including fenchol and borneol, can prevent a batch of terpineol from being considered high grade quality for use in consumer products.
Attempts have been made in the past to sufficiently separate the constituents of pine oil, including the processes outlined in U.S. Pat. Nos. 1,980,030, 2,050,671, and 1,800,862. In particular, the process outlined in U.S. Pat. No. 1,980,030 utilizes ortho-phosphoric acid to react with the terpenic or hydroaromatic alcohols in pine oil to produce the resultant phosphoric acid addition compounds. The resultant phosphoric acid addition compounds can then be separated from the pine oil through extraction, and then saponified back to the original alcohols. However, although the process of U.S. Pat. No. 1,980,030 generally separates the alcohols present in pine oil from the non-alcohols, the process does not allow one to separate the individual alcohols from one another, particularly tertiary alcohols from the other terpenic alcohols in pine oil.
With respect to U.S. Pat. No. 2,050,671, the process therein utilizes boric acid to separate both secondary and tertiary alcohols from pine oil. In particular, the process of U.S. Pat. No. 2,050,671 reacts boric acid with the terpenic alcohols in pine oil to produce the corresponding borates. The borates can then be separated from the pine oil by distillation, and then saponified back to the original alcohols. However, as with U.S. Pat. No. 1,980,030, although the process of U.S. Pat. No. 2,050,671 generally separates terpenic alcohols from non-alcohols present in pine oil, the process does not allow one to separate individual alcohols from one another, particularly tertiary alcohols from the other terpenic alcohols in pine oil.
As for U.S. Pat. No. 1,800,862, the process therein separates secondary alcohols from pine oil, including borneol and fenchol. In particular, the process of U.S. Pat. No. 1,800,862 begins with either preliminarily fractionating the pine oil to obtain fractions in which the secondary alcohols are concentrated, thereby removing most of the other constituents, including terpineol, or dehydrating the pine oil to remove the terpineol. After the secondary alcohols have been further concentrated, the secondary alcohols are then esterified with an organic acid and an acid catalyst, preferably hydrochloric acid, and recovered through distillation. However, although this process separates the secondary alcohols from pine oil, the terpineol is irrevocably destroyed by hydration.
Therefore, there remains a need in the art for a process to effectively and efficiently separate tertiary alcohols from the other constituents in pine oil. In particular, there remains a need in the art for a process to effectively and efficiently separate tertiary alcohols from secondary alcohols in pine oil.